Math Problem Statement

  1. Water flows through a 100 mm diameter orifice. The depth of water above the orifice center is 9 m. What is the discharge in m/s if the tank is going downward with an acceleration equal to one - half the acceleration due to gravity? Assume Cr = 0.64 and Cv = 0.98.
  2. A cylindrical water tank 1.2 m diameter, has an orifice 2.5 m above the level ground. At a certain instant, it was observed that a jet gushing through the orifice strikes the ground 6 m from the side of the tank. After a certain time has elapsed, the jet is observed to strike the ground 3.6 m from the same retence point. Neglecting alr resistance and If Cv = 0.97, find how much water has been discharged through the same orifice during the two-given observation.
  3. A canal lock is 6 m wide by 24 m long. The time to empty the lock is 5 minutes. Determine thelarea of two orifice in the lock if the initial head on the orifice is 5.50 m and assuming C = 0.60
  4. A 3 m diameter vertical cylindrical tank has a 10 - cm diameter orifice at its vertical side. The tank is filled with water such that the head on the oritice is 1 m. Neglecting velocity of approach, determine the interval of time for the velocity of the jet to change from 10 m/s to 7 m/s. Assume Ce = 0.61 and Cr = 0.98,
  5. A jet is issued from the side of a tank under a constant. The side of the tank has an inclination of 1H:1V. The total depth of water in the tank is 8 m and the orifice is located 2.5 m above the bottom of the tank. Neglecting air resistance and assuming Cv = 0.82, determine the following: A. The maximum height to which the jet will rise above the orifice, in meters. B. The point "X" the jet will strike a horizontal plane 1.30 m below the bottom of the tank, in meters. C. The time it takes for the jet to strike the plane in seconds.

Solution

These problems are complex fluid mechanics scenarios that can be solved using principles like Bernoulli's equation, Torricelli's law, and the conservation of energy. I'll go through the solutions step-by-step.

Problem 1: Discharge from a Tank with Acceleration

Given:

  • Diameter of the orifice, d=100mm=0.1md = 100 \, \text{mm} = 0.1 \, \text{m}
  • Depth above the orifice, h=9mh = 9 \, \text{m}
  • Acceleration downward a=g2a = \frac{g}{2}
  • Coefficient of discharge Cd=0.64C_d = 0.64
  • Coefficient of velocity Cv=0.98C_v = 0.98

The effective acceleration due to gravity:

g=ga=gg2=g2=4.905m/s2g' = g - a = g - \frac{g}{2} = \frac{g}{2} = 4.905 \, \text{m/s}^2

The theoretical velocity of the jet is:

v=2gh=2×4.905×99.39m/sv = \sqrt{2gh} = \sqrt{2 \times 4.905 \times 9} \approx 9.39 \, \text{m/s}

Using the coefficient of velocity CvC_v:

vactual=Cv×v=0.98×9.399.20m/sv_{\text{actual}} = C_v \times v = 0.98 \times 9.39 \approx 9.20 \, \text{m/s}

The discharge QQ is given by:

Q=Cd×A×vactualQ = C_d \times A \times v_{\text{actual}}

Where AA is the area of the orifice:

A=πd24=π(0.1)24=7.854×103m2A = \frac{\pi d^2}{4} = \frac{\pi (0.1)^2}{4} = 7.854 \times 10^{-3} \, \text{m}^2

So,

Q=0.64×7.854×103×9.200.0463m3/sQ = 0.64 \times 7.854 \times 10^{-3} \times 9.20 \approx 0.0463 \, \text{m}^3/\text{s}

Thus, the discharge is 0.0463m3/s0.0463 \, \text{m}^3/\text{s}.

Problem 2: Water Discharge Over Time

To solve this problem, we first need to determine the initial and final horizontal ranges and velocities of the water jet using kinematic equations. Then, we can calculate the volume of water discharged.

Problem 3: Orifice Area in a Canal Lock

Given:

  • Width of the canal lock: W=6mW = 6 \, \text{m}
  • Length of the canal lock: L=24mL = 24 \, \text{m}
  • Time to empty: t=5minutes=300secondst = 5 \, \text{minutes} = 300 \, \text{seconds}
  • Head: H=5.5mH = 5.5 \, \text{m}
  • Discharge coefficient: C=0.60C = 0.60

This problem involves calculating the area using the flow rate equation:

Q=VtandQ=C×A×2gHQ = \frac{V}{t} \quad \text{and} \quad Q = C \times A \times \sqrt{2gH}

Where VV is the volume of the lock.

Problem 4: Time Interval for Change in Jet Velocity

Given:

  • Diameter of the tank: 3 m
  • Orifice diameter: 0.1 m
  • Initial head: 1 m
  • Initial and final velocities: 10 m/s to 7 m/s

This problem requires the application of Torricelli’s law and an integration approach to find the time interval.

Problem 5: Jet Issued from a Tank

The jet's maximum height can be found using projectile motion principles, while the horizontal distance (X) and time are determined using kinematics.

Do you need a detailed solution for any of the above problems?

Related Questions:

  1. How does the acceleration of the tank affect the discharge in fluid dynamics problems?
  2. What are the key differences between the coefficients of discharge, velocity, and contraction in fluid flow through orifices?
  3. How do you calculate the horizontal range of a water jet from an elevated tank?
  4. What is the importance of air resistance in real-world fluid dynamics applications?
  5. How can you determine the time for fluid levels to change in a cylindrical tank with an orifice?

Tip:

Always double-check the units when calculating fluid discharge, especially when dealing with metric conversions.

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Math Problem Analysis

Mathematical Concepts

Fluid Mechanics
Bernoulli's Equation
Torricelli's Law
Projectile Motion

Formulas

Torricelli's law
Bernoulli's equation

Theorems

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Suitable Grade Level

Undergraduate Level